You’re right in that there is HasIndex fluent API support in EF - I was looking for it in the wrong place.
I’ve not been able to repro your issue with HasBsonRepresentation though - here’s what I’m doing. If this doesn’t work for you can you provide a small snippet that fails? Thanks!
mb.Entity<PersonWithMultipleLocations>(p =>
{
p.OwnsMany(e => e.locations, f =>
{
f.HasElementName("Locations");
f.Property(g => g.longitude)
.HasElementName("Longitude")
.HasBsonRepresentation(BsonType.Double);
});
});